1. Field of the Invention
The present invention relates to the field of lancing devices.
2. Description of Related Art
For taking a small quantity of body fluid, for example blood and/or interstitial fluid, from a part of a body, for example a finger, for analytic-diagnostic purposes, one normally uses lancets by which the corresponding part of the body is punctured using a lancing system to produce a prick wound.
In order to make such sampling as efficient and least painful as possible, lancing devices usually allow the puncturing depth to be adjusted and, accordingly, to be adapted to a user's personal requirements. On the one hand the puncturing depth must be sufficiently great to allow a sufficient quantity of body liquid to be withdrawn, while on the other hand it should be as small as possible in order to prevent unnecessary pain.
EP 1 427 327 B1 discloses a lancing device where the position of a stop can be adjusted inside the device to stop the puncturing movement and, accordingly, to limit the travel to the length necessary to reach the desired puncturing depth. It is a disadvantage of that arrangement that when the movement of the lancet is interrupted by the stop this may give rise to vibrations that may lead to painful transverse movements of the lancet.
U.S. Pat. No. 6,022,366 describes a lancing device where the length of a lancet holder can be adapted to adjust the puncturing depth. This requires, however, that a cap of the housing has to be removed first, which may be connected with difficulties for many users. Further, this presents the risk of the user being hurt by a lancet present in the device.
US 2007/0055298 A1 discloses a lancing device where a screwed-on end cap is used for adjusting the puncturing depth. That end cap serves as a touching element and has an opening that can be placed on that part of the body in which a prick wound is to be produced. When the screwed-on cap is turned, it moves relative to the lancet drive of the unit, in the puncturing direction, so that a desired puncturing depth can be adjusted. However, it is a disadvantage, of that arrangement that a gap forms between the cap and the device housing when the cap is moved away from the housing in the puncturing direction by a screwing movement. Such a gap is difficult to clean. In addition, contaminations tend to accumulate in such a gap.
Accordingly, there has been a need in the art for a puncturing depth adjusting feature that can be realized in a lancing device without giving rise to the disadvantages described above.